President Obama on Tuesday signed a bill that imposes stiffer penalties for the construction of illicit cross-border tunnels.

The signing of the Border Tunnel Prevention Act of 2012, “is one more step in the Obama Administration’s efforts to strengthen our nation’s border security to deter and prevent smuggling, trafficking, and illegal immigration, while safeguarding and encouraging the efficient flow of lawful trade, travel and immigration,” read a White House statement.

U.S. Rep. Silvestre Reyes, D-Texas, authored the bill that passed the U.S. House of Representatives on May 16 with broad bi-partisan support . Senator Dianne Feinstein, D-California, co-sponsored the senate bill.

“I’ve seen border-tunnels first-hand in San Diego,” Feinstein said last month, according to a statement from her office. “They are much more than simple holes in the ground. Some of them have elevators, electric rail tracks, even a hydraulically controlled steel door.”

Feinstein had previously introduced legislation aimed deterring tunnel construction after visiting one in San Diego in 2006. That bill was signed into law by President George W. Bush, and criminalized the construction, financing or use of an unauthorized tunnel.

The new law notes that since 2006, construction of border tunnels has continued -- 40 in California and 74 in Arizona. The law makes it a conspiracy offense to use, build or finance a border tunnel. It allows wiretaps for tunnel investigations, even if no drugs or other contraband have been found. It also permits law enforcement officials to invoke money laundering laws when seizing assets in tunnel-related cases.

The new law “will close loopholes and drastically improve the tools available to investigate and prosecute individuals who construct cross-border tunnels, as well as allow for the forfeiture of bulk cash and merchandise that enters the United States through these illegal channels,” according to a statement Tuesday from Reyes’ office.